Computer networks comprise multiple computers that are interconnected for communication with each other. A network may include only a few computers physically located close together or it may include many computers dispersed over a wide area. A network may include subnetworks or local area networks (LANs). A network also may include widely separated computers interconnected over a wide area network (WAN). Routing devices, in essence, are specialized computer networking devices that route or guide packets of digitized information throughout a network. Typically, when a host computer sends a packet out onto a network, it includes in the packet address information that specifies the source of the packet, the sending host, and the intended destination of the packet, another host computer connected to the network. The sending and receiving hosts ordinarily are interconnected through routing devices which use packet address information to route packets through the network from one routing device to the next en route from the sending host to the receiving host. Routing devices, therefore, perform a complex and critical role in network operations.
In many environments, networks are subjected to almost continual changes as host computers are added or deleted, for example. Unfortunately, networks are susceptible to failure. In today's information based economy, network failure can have severe implications to organizations that rely upon computer networks as a primary conduit for information. Network management is the process of maintaining the integrity of a network. It involves functions such as, observing the state of a network, monitoring network traffic, troubleshooting the network, making changes to the network and ensuring that the changes have the desired effect. Network management has become increasingly important as the size, diversity and importance of computer networks have grown. The rise in prominence of the Internet underscores the importance of high quality network management.
Complex technical challenges are an inherent feature of the network management function. For instance, network components may be diverse and physically dispersed. Many different communication protocols may be used simultaneously over the network. Security issues play a role in communications between hosts connected to the network. These are just a few of the numerous factors that combine to define the environment in which network management takes place. Some of the more routine objectives of a typical network manager include the swift analysis of large volumes of data, troubleshooting problems in a timely fashion, and implementing changes or upgrades without disruption of normal network operations. Numerous network management tools are available to aid in achieving network management objectives. For example, there are tools that monitor network traffic and tools that monitor management information base (MIB) data. Configuration management tools can produce audit trails that indicate the history of changes to routing device configurations. There are network management stations that can collect information from network probes and present a network manager with data representing the state of the network. Simulation tools can predict the performance and behavior of hypothetical networks. Topology rendering tools can be used to identify possible problems on particular network components as well as network-wide problems.
There are particularly difficult technical challenges in the realm of network management tools that identify possible network-wide problems and that render network topologies. For example, it can be difficult to determine the logical connections between network devices without requiring a live operational network. Additionally, the problems associated with providing a network centric view of potential problems in a network are significantly greater than the problems associated with testing an individual network component for potential problems. Moreover, diagnosing routing table problems may involve complex inquiries aimed at identifying routing loops and identifying dead end paths, for example. Furthermore, security issues involving router access lists can be difficult to diagnose without a relatively comprehensive understanding of the operation of the network containing routers with such access lists, so that, for instance, a route around a blocked host can be tracked.
Thus, there has been a need for improved network management tools that can provide network centric analysis of potential problems and that can provide diverse views of network topology in order to enhance a network manager's ability to manage a network. The present invention meets this need.